The present invention relates to a coating composition for protecting and dressing building materials which possesses excellent workability and is capable of producing a hardened, coating film having excellent performance and high utility in protecting and dressing indoor and outdoor walls of buildings.
Coating materials for dressing the indoor and outdoor walls of buildings which have been heretofore used can be classified into organic types and inorganic types according to the type of the binder used therein. The binder used in an organic type coating material generally is an acrylic resin emulsion or a vinyl acetate type resin emulsion. The film resulting from a coating material containing such a synthetic resin binder has low fire resistance and inadequate weather resistance, water resistance, strength, and alkali resistance. Further, it is easily soiled because of its high stickiness. On the other hand, the inorganic type coating material generally contains cement-based binders. Such cement-based binders harden on hydration. Therefore, water must be added and mixed into the coating material immediately before the application thereof. For this reason, the inorganic type coating material gives rise to difficulties in its use and, further, causes effloreescence.
In recent years, a coating material composition containing a binder composed mainly of silica hydrosol (colloidal silica) has been proposed for overcoming the above mentioned difficulties. However, the proposed composition has been found to be still unsatisfactory in film hardness, water resistance and weather resistance.